Playing organized football before age 12 may have significant behavioral and cognitive consequences in adulthood, new research suggests.
The study shows that children who began playing the game before age 12 had a threefold increased risk for depression and a twofold increased risk for impaired behavioral regulation, apathy, and impaired executive function compared to their counterparts who started playing at age 12 or older.
Early adolescence is a critical time for brain development, and mounting research suggests that exposure to repetitive head impacts during this period may disrupt normal brain maturation and increase vulnerability to long-term clinical impairment.
"I don't think it makes sense to have our kids be exposed to repetitive head impacts during a period of neurodevelopmental vulnerability," study author Robert A. Stern, PhD, professor in the Departments of Anatomy, Neurobiology, and Neurosurgery, director of the Alzheimer's Disease Center, and director of clinical research, Chronic Traumatic Encephalopathy Center, Boston University, in Massachusetts, told Medscape Medical News.
Much recent attention has focused on concussions, not on repetitive head hits, said Dr Stern.
"There has been a really good focus on concussion and concussion awareness and reducing concussions and managing them better, but that's not really doing anything in regard to the repetitive hits that don't result in concussion."
The study was published online September 19 in Translational Psychiatry.
The analysis included 214 male former football players (mean age, 50.68 years; 89.7% white) from the ongoing Longitudinal Examination to Gather Evidence of Neurodegenerative Disease (LEGEND), a registry of living active and former athletes.
The sample included only those who had played high school, college, or professional football, who had not participated in any other organized contact sport, and who had not had a concussion within a year of their initial LEGEND interview.
About 9% of the study sample had a learning disability, 60% had been diagnosed with a psychiatric disorder, and 36% were taking a psychotropic medication. The mean age at first exposure (AFE) to football was 11.12 years.
The measures used in the study included the following:
The Brief Test of Adult Cognition by Telephone (BTACT), a 20-minute telephone-based objective assessment of cognition. The test evaluates episodic, verbal memory, working memory, semantic fluency, task switching, inductive reasoning, and processing speed.
The Behavior Rating Inventory of Executive Function-Adult Version (BRIEF-A), a self-report instrument that measures executive function behaviors. Researchers assessed both the behavioral regulation index (BRI), which includes impulsivity, and problems with emotional regulation. The metacognition index (MI) was used to assess cognitive functioning, such as organization, multitasking, and initiation of activities.
The Center for Epidemiologic Studies Depression Scale (CES-D), a self-report checklist of depressive symptoms.
The Apathy Evaluation Scale (AES), a self-report measure of cognitive, behavioral, and emotional symptoms of apathy.
Age 12 Tied to Most Robust Findings
The investigators found that compared with those whose first exposure to football occurred at the age of 12 years or older, those whose first exposure occurred before that age had significantly higher (ie, worse) scores on the BRIEF-A BRI (adjusted P = .001), the BRIEF-A MI (adjusted P = .016), the AES (adjusted P = .002), and the CES-D (adjusted P = 0.001), but not on the BTACT (P = .35).
In multivariate logistical regression models in which participants whose first exposure to football occurred at an age younger than 12 years were compared with participants with later AFE, the odds ratios (ORs) of clinically meaningful scores were as follows: 2.16 for the BRIEF-A BRI ( P = .016); 2.10 for the BRIEF-A MI (P = 0.016); 2.39 for the AES (P = 0.010); and 3.08 for the CES-D (P = .002).
There were no significant effects in these models on BTACT (P = .54).
It was unclear why differences in scores on the BTACT, which was the only objective measure of cognitive functioning used in the study, failed to reach significance.
"It could be that if we examined people in person using more extensive neuropsychological tests, it would have had a greater ability to pick up on things," said Dr Stern.
When examining AFE to football as a continuous variable, "we found that overall, the younger someone started playing, the greater the odds of having problems later in life," said Dr Stern.
The results were independent of the number of years the participants had played football as well as the level of football played (high school, college, or professional).
Results were unchanged when a history of learning disability was included as a covariate.
The researchers could not analyze possible effects of different positions played, but Dr Stern noted that young football players typically play all positions.
Although outcomes such as depression and apathy are connected (for example, having depression can cause apathy, and vice versa), the statistical models took this intercorrelation into consideration, said Dr Stern.
Although the researchers used 11 years and 13 years as cutoff ages, "age 12 consistently resulted in the most robust findings," said Dr Stern.
Age 12 also was a critical cutoff point in Dr Stern's previous research that included former National Football League (NFL) players. In one study, the researchers compared pairs of age-matched players, one of whom started playing football before age 12 and the other at age 12 or older. Players who had started earlier had significantly worse memory functioning and mental flexibility.
Another study they conducted showed that persons who started playing before age 12 had significantly worse microstructural integrity of the corpus callosum.
Previous research has shown that from the ages of 9 to 12 years, boys' brains undergo tremendous changes in gray matter and white matter volume and in synaptic and neurotransmitter density.
Playing football at this stage of development often means experiencing significant hits to the head. One study cited by the authors, which used helmet accelerometry, showed that young football players experience an estimated median of 252 head impacts per season.
Dr Stern noted that today, children often play football all year round, whereas in the past, they would play only during the fall season.
Research is uncovering the degree to which multiple hits to the head occur while playing football. Dr Stern pointed to one recent study of young football players who had not experienced concussions. The study utilized accelerometers in the helmets as well as brain imaging, including diffusion tensor imaging. The results were "striking," he said.
"It found this really strong relationship between the overall exposure to repetitive hits and changes in the integrity of the white matter ― from just one season of youth football playing."
But perhaps the game of football is safer today than it was when these older men played youth football, given advances in safety.
Dr Stern acknowledged that helmets and face masks are now "bigger and stronger," but while this new equipment might prevent a skull fracture, "it doesn't do anything to protect the brain from moving around."
Also, the new equipment might give young players "a sense of invincibility" because they don't feel the pain when they hit their head repeatedly, he said.
"I don't think the game is necessarily safer when it comes to the repetitive hits."
Dr Stern noted that he is not a policy maker and insisted that the choice to enroll a child in a football league is "personal" and should be made by parents.
"The decision should not be made in a knee-jerk fashion due to a single study like this one."
But the growing evidence might make parents ― and clinicians ― take heed.
"We do so much as clinicians and as parents to protect our kids from injuries, from illness, and to make sure that they live up to their full potential," said Dr Stern. "But then we drop kids off at a playing field at the age of 5 or 6 or 7 and tell them to put on this big helmet and to hit their friends in the head over and over again. We have to remember that inside those heads that are getting hit is the most precious organ in the body ― the brain."
Critical Questions Remain
Commenting on the findings for Medscape Medical News, Alexander S. Strauss, MD, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey, who is an adult, child, and adolescent psychiatrist specializing in the implications of concussion on mental health, said the study contributes to the growing body of literature regarding the long-term consequences of playing football.
Dr Strauss noted that unaddressed factors may contribute to the later development of symptoms of behavioral problems, apathy, and depression in persons who play football at an early age.
"Perhaps parents put children with behavioral problems into football at a younger age. By being a retrospective study, we won't know."
It is also unknown, he added, whether some athletes who played football at an early age identify as football players and then later, as adults, "feel more depressed and apathetic because they can't play anymore."
But he noted that youth football organizations are taking into consideration new research on the effects of head hits. For example, in 2012, Pop Warner Little Scholars became the first youth football organization to officially limit contact during practices.
Despite this new study, questions remain, said Dr Strauss.
"Are their critical periods during which the risks are higher? Possibly, but is that age 2, 5, 15, or perhaps age 12, as this study indicates? Are certain people more prone to hit their heads? Do people who have behavioral problems, hyperactivity, and impulsivity hit their heads more?"
A lot of work needs to be done to answer such questions, said Dr Strauss. "Thankfully, more and more people are focusing their research on this important topic."
Until more is known, it's important to protect the brain. It is also important to remember that sports in general "can be amazing for the growth and development of youth," said Dr Strauss.
"Our goal should be to make all sports safer, so everyone interested can participate in a healthy way, with limited risk."
Dr Stern is a member of the Mackey-White Committee of the National Football League Players Association. He is a paid consultant to Avanir Pharmaceuticals, Eli Lilly, and Biogen, is a member of the board of directors of King- Devick Test, and receives royalties for published neuropsychological tests from Psychological Assessment Resources. Dr Strauss has disclosed no relevant financial relationships.
Transl Psychiatry. Published online September 19, 2017. Full text
Medscape Medical News © 2017
Cite this: Football in Childhood Tied to Cognitive Disorders in Adults - Medscape - Sep 20, 2017.